Another female band I really like that no one has ever heard of is: Antigone Rising. Their "From the Ground Up" CD is AWESOME! They're incredibly talented and put on an awesome live show, but not a lot of amped up workout music.

hmm i really love riot grrrl music so here's a list of bands you should check out:

Sleater-Kinney (absolute fave band in that genre)
babes in toylandbikini kill - check out the song rebel girl
blue foundation - check out the song eyes on fire
bratmobile
hole - they did celebrity skin
jack of jill
L7
Lash
Le Tigre

Nightwish is my number one female-fronted band. Yes, the band is made up mostly of men(yummy eye candy at that. ) but that doesn't mean that it's all aggressive. Bye Bye Beautiful and Sahara are 2 of the best songs I think, as well as Wishmaster(makes ya laugh if you've never heard the song before)Um, Planet **** is another good song, nice and upbeat. There's so many goodies to choose from. Ooh, and I should also mention Fantasmic, Britney Spears actually used the intro of that for one of her gigs in Copenhagen, Denmark. Did I mention that I'd seen Nightwish live? OMG they kick butt!!!!!

Arch Enemy gets played when I'm on the rag, simply because it's aggressive and touches my pain. Another 'once in a while' band i adore is Lacuna Coil.

I've recently got into this solo artist named Lenka. She's got a slightly more popish slant to her style, though, so she might not be for everyone. My two favorite songs by her at the moment are: The Show, and Trouble is a Friend.

I personally have a hard time listening to chicks backing up most genres of rock and metal because they make it sound too pop. (I am a girl, btw) BUT...

Nightwish (with Tarja Turenen...Anette is ok, but not nearly as good. Try Phantom of the Opera and Wish I Had an Angel first.)
Tarja's Turenen's solo album
Krypteria (Scream is a good intro song.)
Leaves' Eyes
Emilie Autumn (she's a bit of an acquired taste...Try Thank God I'm Pretty and Marry Me to see if she's your thing. Her instrumental-only songs are good if you hate her voice. She plays an electric violin!)

Most of the bands I like have male-fronted vocals, though occasionally they use girls for backup. For instance, Kamelot is a great band that occasionally slips in some female vocals to contrast with Khan's voice.

Concrete Blonde - Bloodletting : I love this one if I'm feeling all gothy and nostalgic.Poe - Haunted : This is one of my favorite albums ever. Few people know about it, but everyone should. Every song on this album is awesome.Republica This album has a relentless techno beat, with a cool pop/rock melody on top.

I love Lita Ford and Janet Jackson too, of course. They remind me of being 10 and wanting to grow up to be them some day. haha I'm still working on the growing up part.

I also love those old country story songs by tough redneck chicks! You know, songs about murder, birth control, drinking, prostitution and love? hahaha Women like Loretta Lynn, Emmylou Harris, Dolly Parton, June Carter Cash, Jessi Colter and Bobbie Gentry were singing about that stuff when it wasn't OK to TALK about it! If you're not familiar you might want to check some of it out. It's more "Americana" than "Country". Think Johnny Cash rather than Shania Twain. Makes me feel like a badass after a little bit of singing along.

BUT I would really recommend supporting your local artists. Most towns are going to have girl bands nowadays. Go and see them! Buy a CD! Let them know they rock as hard as the boys!